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Observations on the Ringing Rocks
The following is a laundry list of mostly unpublished observations on both the Pennsylvania and Montana ringing rock sites. These observations were made by myself from over twenty five years of field and labratory work, but most have not been peer-reviewed in any way. Some established ideas were copied into the main article page and included here to make it easier for non-geologists to understand. Since they are mostly not published I am placing them in the Talk section, rather than giving them the weight of facts in the Article section. I gladly invite any comments or corrections.
1. Although mafic in composition (approximately 55-60% silica, 7-12% iron), the rocks do not have an unusually high iron content. The majority of the iron in both the Pennsylvania and Montana rocks is chemically bound up in the pyroxene crystals (iron magnesium aluminum silicate).
2. The boulder fields are in-place, and the boulders have not been transported by glaciers, flow of water, soil.creep, or solifluction. Often the individual boulders were floated and rotated by snow and ice accumulation during the periglacial development of the fields, however the boulders typically did not migrate out of the fields. The farthest extent southward of any glacial sheet in the area was approximately 15-20 miles north of any of the Pennsylvania ringing rock boulder fields. The boulder fields in Pennsylvania could not have been caused by solifluction, because the boulders higher up on the hills are composed of a different type of diabase.
3. The boulder fields are naturally occurring geologic features, and were not created by government 'make work' projects or mysterious ancestors. The Pennsylvania felsenmeers are relics of an extreme periglacial environment that existed over 12,000 years ago and are now surrounded by temperate forests. In comparison modern felsenmeers and tors are found in severe cold latitudes such as northern Alaska or Iceland.
4. The boulder fields are not ancient fortifications. Typically a mixture of the light colored clay mineral montmorillonite and caliche (lime) is naturally washed off of the boulders by rainwater and deposited in cracks of the underlying Brunswick Formation below, leaving (for some observers) the impression that the underlying rocks were part of a mortared wall.
5. The boulder fields do not exhibit unusual 'energy' fields, including electric, magnetic, or radiation. The rocks do have weak magnetic fields due to the presence of the trace mineral magnetite (iron oxide: Fe3O4), however the effect is very minor. Many igneous rock types contain small amounts of magnetite. Nick Reiter (2006) did a very nice field study of the Pennsylvania Bridgeton site and did not observe any unusual types of energy.
6. The boulder fields do not interfere with radio communications.
7. The boulder fields are not completely devoid of life. Lizards, insects, lichen, birds, and other life can be seen on occasion. Because the rock types do not produce soil very easily and the flushing process of the felsenmeer there is very little opportunity for plants to grow in the boulder fields. In addition, animals tend not to venture into such inhospitable areas where there is little food. The boulder fields have a similar amount of life as a concrete parking lot would have, and for the same reasons.
8. The boulders are not hollow. Typical ringing rock boulders can weigh many tons.
9. The ringing sound is not metallic, but is due to a combination of a dense tough rock type and internal stresses. The sound can be reproduced on a small scale by tapping the handle of a ceramic coffee cup.
10. The boulders continue to ring when removed from the boulder fields. Myths have been developed by authorities to discourage the theft of boulders from the fields. At the current stage, however, most fields have been picked clean of small portable 'ringers', and breaking of large boulders into smaller pieces releases the internal stresses - thus causing them to stop ringing (ie, breaking a piece off of a large ringing rock will only gain a dead chunk of rock and destroy a natural curiosity forever.) 'Small' ringers found today weigh over a ton, and would have to be dragged out of the boulder fields using large equipment.
11. Simply stacking boulders of any rock type into a loose pile will not create ringing rocks. The boulders must be a very specific composition (in this case olivine diabase, but others have the necessary requirements), and the boulders must have the proper conditioning (internal stresses). Without these special conditions loose rock boulders will only provide the familiar 'thud' when hit.
12. Microscopic and chemical analysis show that there is no difference between the 'live' and 'dead' rocks. Examinations of rock thin sections did not reveal any tension fracture fabrics in either the Pennsylvania or Montana rocks.
13. The "slow weathering" theory was a creative attempt by a non-geologist physics professor to explain the source of the stresses which he successfully identified. The problem was that he envisioned the ringing rock boulders as elastic rubber balls which could be deformed. In reality, igneous rocks do not take deformation very well at all. Rocks are composed of interlocking grains of hard mineral crystals, and changing the shape of a rock simply breaks the internal structure. Rocks are very weak in tension (usually 30 times stronger in compression than tension), which is why reinforcing steel bars are placed in concrete (essentially an artificial rock). In compression the interlocking bonds snap and the rock disintegrates. Metamorphic rocks occur in nature through extreme amounts of temperature, pressure, and fluids, and the mineral components usually recrystalize (ie relock). The compressdional stresses in the ringing rocks would have had to be present when the rock crystalized.
14. There is no source on the surface of the Earth which could have created the compressional forces needed to create the ringing rocks. Really the only place where forces of that magnitude can be found are miles beneath the surface. Nearly all other rock types lose the compressional stresses when exposed to the surface because they are not 'tough' enough to retain them. The diabase and olivine pyroxene monzonite both exhibit an amazing combination of density, toughness, and mineral size and composition (primarily pyroxene) which allows them to hold on to the stresses without breaking.
15. The balance of requirements needed to create the ringing rock boulder fields is extraordinary. Take this very specific and unusual rock type and add the requirements that the boulders have to be 'stored' in a dry environment where they are isolated from weathering, and the strangeness of the boulder fields becomes apparent. This specific balance also accounts for the rarity of the phenomenon.
In the Pennsylvania fields, the rock is found only is a very thin cumulate layer along the base of a diabase sill which is usually 1,000' thick. To get enough of the material together to form a boulder field the precise structural dip of the unit had to intercept a slight slope of the ground, which happens rarely and only for short distances. The boulder fields formed exclusively in a very narrow band of outcrops in the west end of the Newark Basin. Diabase sills in the east Newark Basin were buried under the ice sheets and the outcrops were obliterated. In the Gettysburg Basin 20 miles southwest the periglacial effect apparently was not severe enough, because ringing rock boulder fields did not form there despite it having the necessary outcrop configurations.
In the Montana sites, the rock is the result of a series of very exotic volcanoes which erupted at the transition time between the Elkhorn Volcanics and the Boulder Batholith series intrusive plutons. The volcanoes probably started as diatremes, because they have very extensive contact auroles for their size. A flow of olivine basalt and granite magmas, two types of magma which normally don't mix because their component minerals crystalize at extremely different temperatures, inexplicably mixed very thoroughly and the hybrid magma was plastered against the outer walls of the conduit in layers. The hybrid magma was then quenched very rapidly, possibly by the escape of volatiles through the central portion of the conduit. For the Ringing Rocks Pluton, the cooling came in pulses, because there are distinct layers in the hybrid units. In layers where the cooling was rapid, all of the minerals were 'frozen', so that minerals such as magnesian olivine and quartz are found together with only minor alteration. More importantly, the high temperature early minerals, olivine and pyroxenes, remained intact. In the layers where the cooling occurred more slowly, the minerals came to a thermal equillibrium. The olivine and pyroxene crystals were converted to fine grained masses of amphiboles (usually anthophyllite, a metamorphic orthoamphibole). This hard-soft-hard-soft layering is the reason that the tors were able to form when uplift and erosion brought the rock to the surface millions of years later. The olivine-pyroxene hybrid rock was extremely resistant to weathering as long as it did not come in contact with moisture and/or acidic soil. The amphibole hybrid rock was so weak that it disintigrated to a coarse soil wherever it reached the surface. Each of the layers were approximately 20' thick. Erosion by Dry Creek had to be very nearly at a right angle to the strike of the vertical olivine hybrid so that the amphibole hybrid rock could be stripped away, and the walls could form. The olivine hydrid outcrops were about the perfect thickness: thicker and they would not have been so completely broken down by frost wedging; thinner and they probably would not have had enough material to form the tors. The tors had to be of sufficient size to keep the boulders isolated from the soil. Glacial cover would have destroyed the outcrops, and the periglacial period was sufficient to break down the walls of olivine hybrid rock. A more perfect balance of precise events would be hard to imagine.
16. Boulders in the fields can occasionally be seen which have 'popped', ie split into quarters, through expansion/decompression.
17. Interestingly both the Pennsylvania and Montana rocks are composed of a combination of two different pyroxenes: augite (clinopyroxene), and hypersthene (orthopyroxene). (Both Butler 1983 and Johannesmeyer 1999 incorrectly identified the Montana clinopyroxene as salite, a pyroxene commonly associated with alkaline intrusions.)
18. Diabase is a type of basalt which crystalizes beneath the surface, as opposed to basalt surface flows. Although the chemistry is commonly similar, diabase usually undergoes different crystalization processes due to added temperature and pressure than basalt is subjected to at the surface.
19. An impressive feature of both the olivine diabase and the olivine pyroxene monzonite is the extent of breakage in the outcrops by frost wedging. In all of the Pennsylvania and Montana sites there are virtually no outcrops to be seen. The only exception has been an outcrop at the Devil's Potato Patch (Fulshaw Craeg Preserve - private land) near Quakertown PA. A possible reason is that the pyroxene-based rock is suseptable to chemical weathering along the joints, the same weathering which creates the odd textures on the boulders. The weathering possibly allows blocks of material to be drawn away from the outcrops more easily than a quartzite rock which does not chemically break down.
20. The archaic term olivine pyroxene monzonite for the Montana Ringing Rocks Pluton was used as not to skew the interpretation of the rock type. Modern igneous classifications use whole rock chemistry to categorize rocks, however the hybrid nature of the Ringing Rocks mafic units makes that approach difficult. The rock has been referred to as a mafic monzonite, shonkinite, black gabbro, and black granite in different literature. Many informal field reviews refer to the rock as a gabbro, which it is not.
There is a ringing rocks park in Mexico called the Hill of the Bells. If someone could translate the following page and provide a summary of it here then the Ringing Rocks page would have more depth.
In the feature on cable tv's "Travel Channel" it is noted that the rocks cause interference with compass activity thus implying a magnetic force being exerted; I am wondering if the ringing tone "like a bell" can be caused by a high iron (Fe) content or some other metal. It is curious though that a rock will cease to ring when taken away from the rest of the rocks- possibly due to interacting resonace between the rocks to create an audible tone as noted in the article? Interesting stuff.
A link was present for Ringing Rocks Park with no article created. Since there is already a section on RRP in this article, a seperate article is probably not necessary. ndyguy 22:58, 12 August 2006 (UTC)
Merge and redirect
- I support that, unless they can be proven to be significantly different. Kortoso (talk) 23:09, 19 January 2016 (UTC)
Very simply, ringing rocks are a geologic formation, a lithophone is a musical instrument made of ringing rocks. — Preceding unsigned comment added by Andrews66 (talk • contribs) 03:55, 21 January 2016 (UTC)